Re: Matrix-Multiplication: Security?

Douglas A. Gwyn <DAGwyn@null.net> wrote:
> Anton wrote:
>> I've written a Delphi-program to encode textmessages with
>> matrix-multiplication. The decoding-matrix is the inverse matrix of the
>> encoding-matrix. You can choose a n-dimensional matrix.
>> Now I'm wondering how secure this method is. How can I translate the
>> "security" in bits (like "128 bits")?
>
> Approximately 0 bits?

Don't you think that's being a bit unfair? You can't break his cipher in
O(1) time -- you can't even read the data that fast.

I'd say that his cipher is 2 log_2{n} bits strong against a chosen
ciphertext attack, and 3 log_2{n} bits strong against other attacks. :-)

Colin Percival
Received on Thu Sep 29 21:39:01 2005